Drawdio Problems and Suggestions

[rben13]

Hi,

This kit looks like a wonderful teaching toy, but getting it to work has been mildly frustrating. I wouldn't let that stop you from getting it, but it might be a wise thing to buy an extra and put it together before introducing this to your kids, so that you know where the potential pit falls are. Having another kit for spare parts isn't a bad idea, either.

I just finished working with a couple of young girls (9) I tutor, putting together a Drawdio. Predictably, we had some problems, but that's part of learning. There were two problems, though, that I think could have been avoided.

First, we mounted the speaker directly to the PCB following the suggested method. Later, when one of the girls dropped the drawdio on the floor, it hit on the edge of the speaker and the contacts on the speaker itself sheared off. Fortunately, I had a second Drawdio kit. This time I used the wires to attach the speaker, but I also glued them to the back of the speaker using Gorilla glue (made from the finest gorillas). Gluing them will, I hope, reduce the force applied to the contacts. I considered gluing the speaker to the PCB as well, but figured that leaving it loose would allow the speaker to move the next time the device is dropped, reducing the force of impact. I would suggest using higher quality speakers, if possible, and/or recommending that the user glue the wires down to the back of the speaker as I did. (By keeping the wires short, you can wind up with the speaker in the same spot as it would be if you mounted it on the PCB. Just be sure to cut the wires to length after you solder them to the speaker and glue them down.

The other problem was getting the tack in just the right spot. Because the end of the pencil is painted over, it's hard for small hands and inexperienced eyes to make sure the tack hits the graphite. I suggest adding an optional step where the user cuts off a millimeter or two off the painted end so they can see where the graphite is. Alternatively, they could simply reverse the pencil and put the tack in the other end.

I think it would also be a good idea to add a briefer from of the excellent instructions you provide, perhaps a recapitulation at the end of the instructions with links back to the details.

Finally, the one problem I haven't been able to solve is that no matter how I place the tack in the end of the pencil, we don't seem to get a reliable connection. Everything up to the graphite tests just fine, but we don't always get sound out when touching the tip of the pencil or the drawings. (The other hand is on the copper tape.) I've tested with my continuity checker, and the graphite path from tip to tack seems fine. So, I'm confused about that.

[adafruit_support_bill]

Thanks for the feedback.

we don't seem to get a reliable connection. Everything up to the graphite tests just fine,

Other things that can affect conductivity:

Skin conductivity - Sweaty hands are a plus here.
Paper surface - If it is too smooth, it will be hard to lay down enough graphite to be conductive.
Pencil - The 2B pencil in the kit is pretty good, but there are softer drawing pencils too. Carpenter's pencils work well also.
Coin - You can improve contact between your other hand & the graphite on the paper using a coin.

[wakeupsilver]

Here are some tips for Drawdio'ing
http://drawdio.com/start_drawdio-ing.jpg

make sure to draw your lines dark and use a smooth hard surface behind the paper

(:

good luck

[aitchk]

PROBLEM: Drawdio kit 1.1 – works only if paper is covered in film of water
That’s pretty much it.
For our Drawdio pencil to work we have to brush a thin film of water across the surface of the paper. Only then will current conduct along the graphite line. If the pencil line drawing goes beyond the wet area the sounds stops. We have also tried the coin idea posted here. It appears that the paper’s resistance when dry is greater then the resistance of one or more human bodies ie. when we added a second body to the circuit (and no paper).
We tried two different kinds of paper: medium weight printer paper and cardboard. Since the paper we saw in videos didn’t appear to be anything special, we didn’t try an exhaustive list of different types of paper.
We did try adding a second C2 capacitor. The only change that this brought about was to lower the pitch of the sound.
Has someone had the same experience? Can someone help provide a systematic approach to isolating the reason why the Drawdio is not strong enough to overcome the resistance of the paper?

[adafruit_support_bill]

Can someone help provide a systematic approach to isolating the reason why the Drawdio is not strong enough to overcome the resistance of the paper?

It is not the paper that needs to be conductive. It is the graphite from the pencil. Glossy paper will not hold enough graphite. Rough textured paper can cause breaks in the continuity of the graphite line. An average grade of copy paper or smooth textured sketchpad paper typically works well.

[aitchk]

It is not the paper that needs to be conductive. It is the graphite from the pencil. Glossy paper will not hold enough graphite. Rough textured paper can cause breaks in the continuity of the graphite line. An average grade of copy paper or smooth textured sketchpad paper typically works well.

I am sorry that I gave the impression that I thought the paper itself was the conductor, as I do not. Rather I think of it as the substrate. Also, I believe I said I used medium grade printer paper (not glossy) and also cardboard, which is NOT glossy. In the course of experiments I have made sure to create huge black blobs of graphite, to expend much energy pushing it into the paper and making sure there was enough of it to conduct the current. The moment the tip of my moving finger leaves the tip of the pencil's graphite the sound stops. The current just has no stamina if you will, unless i add a film of water for it to skate across OR eliminate the paper altogether and just join bodies.

Any other ideas? I would **really** like to get this working AS SEEN ON YOUTUBE as I see it as the 'gateway' toy to AdaFruit.

[adafruit_support_bill]

Extreme measures shouldn't be required to get sounds from it. If you post photos of the front & back of the board we can check the assembly.

[aitchk]

Extreme measures shouldn't be required to get sounds from it. If you post photos of the front & back of the board we can check the assembly.

I would like to attach a photo but am getting error message from this forum website "The image file that you are trying to attach is invalid". It is a .jpg file and both BBCode and [img] settings are ON.

I agree that there shouldn't be extreme measures. I did find a carpenters pencil to which I remounted the assembly and found smooth non glossy artist sketch paper and drew a honking thick line across it with finger implanted on one end, and graphite firmly pressing to paper as I drew line. Once again, as soon as the connection between left hand (non-drawing hand) and pencil is broken, the sound stops.

BTW, when I use water on paper, the graphite line is irrelevant. Water and bodies conduct the current just fine. The problem must be with the assembly.

I have contacted the forum admin so I can post the photos of my assembly. Thanks for your help.

[adafruit_support_bill]

Here are the photos. They didn't upload because they were too big, so I resized them. From the top, it looks like everything is in the right place and the solder connections we can see look fine. A photo of the other side would be helpful to check the rest of the soldering.

The only other suggestion is to make sure you have a fresh battery in it.

[aitchk]

Well, the battery holder is soldered to the back of the PCB....BTW just tried new battery with no improvement....
Before I try to undo my work, which I don't know how to do, please tell me which contact points you are specifically curious about. Clearly, current is conducting because the Drawdio works with water and human bodies. So, which contact points would be specifically of interest once i tear this thing apart, perhaps irrevocably?
Is it possible that the circuit provided is overall inadequate for handling slight weakening of the strength in current that may result due to slight variations in the assembly? Ditto for capacitor? If the answer is no, please explain.

I believe the soldering joints are well done as they mounded nicely. BTW, used *lead* solder.

ps. this is discouraging for what is supposed to be an easy beginner project.

[adafruit_support_bill]

I'm sorry you had a bad experience with this kit. We do sell a lot of them and most go together without problems. Contact support@adafruit.com with a link to this thread and ask for a replacement kit.

[aitchk]

I'm sorry you had a bad experience with this kit. We do sell a lot of them and most go together without problems. Contact support@adafruit.com with a link to this thread and ask for a replacement kit.

Wow, thanks! I emailed. Really appreciate it.

[aitchk]

Sorry it's been awhile. I *did* get the second Drawdio in the mail (very nice of Adafruit) and I assembled it again, and I am having the same problem. I did the assembly under the direction of an electrical engineer so the chances of it being done properly are good, however, there is no way that so many people could have successfully assembled and tested their Drawdio unless they did something that I didn't do, properly.
Two scenarios:
1) When I eliminate lead contact, ie. make contact with the copper tape with one hand, and the end of the wire with the other, noise happens.
2) When I imitate the Drawdio videos, attaching the end of the wire securely to the 6B lead, making contact with the copper tape with drawing hand, and making finger contact with the tip of the lead pencil with the other....no sound.


Is it possible that the assembly is wrong, even with scenario 1 being true? The only problem seems to be the graphite, yet I am using the recommended softness.

UG. It must be something I did but I don't know where to begin to troubleshoot.

[adafruit_support_bill]

Hmmmm If you get a sound touching the wire, the circuit itself is most likely working properly. It could be that the tack in the end is not making good enough contact with the pencil lead. One customer reported better results using a metal-bodied mechanical pencil.

[aitchk]

I'm assuming that the other user's suggestion is based on the mechanical pencil's metal body/casing making good contact with its' lead....sure would be nice if someone did a utube showing end-to-end set up of either solution.
The concept of a paintbrush working escapes me even more. For a paint brush to work, wouldn't you have to insert the wire from the circuit into the bristle hairs which themselves would need to be thoroughly wet in order for the current to conduct?